Measuring tool and gauges used to measure various parameters such as clearance, diameter, depth, thickness, runout etc. These are critical engineering parameters, which describe the condition of the working machinery.
For Example:- For measuring brake pad and brake disc thickness, Micrometer or Vernier calliper used. Bore gauge used For measuring cylinder bore. Feeler gauge mainly use to measure piston ring clearance, engine bearing clearance. Depth gauge are use to measure the thread depth of tyre
Some important measuring tool and gauge
Vernier Calliper considered one of the precise measuring tool which is use to the car mechanics shops because of its accuracy. Car technician also use Vernier calliper when they are repairing a car and have to change a part for which the need it’s measurement.
It has got two different jaws to measure outside and inside dimensions of an object. It can be a scale, dial or digital type Vernier calliper.
Calculation of least count:-
Least count of the Vernier calliper is the difference between the values of main scale division and one Vernier scale division.
Least Count = Value of one main scale division – Value of one Vernier scale division.
= 1 mm – 1/10 mm = 1 mm – 0.1 mm = 0.1 mm or 0.01 cm
So final least count of Vernier calliper is == 0.1 mm or 0.01cm
Note** It is not necessary to have same least count for all Vernier calliper.
Type of Vernier calliper
Use of Vernier calliper in automobile
Vernier calliper is mainly use to measure thickness of brake pad, brake disc, wear limit of any parts, inner diameter and thickness of cylinder, depth of tyre etc.
A micrometer is a measuring instrument that can make extraordinarily precise measurements. It is an excellent precision tool which is use to measure small parameters and is much more accurate than the Vernier calliper.
Exact measurements is possible through micrometer even when the smallest of space between objects can cause problems or difficulties. The micrometer size can vary from small too large. The large micrometer calliper is use to measure large outside diameter or distance.
Mainly two types of micrometer available
**The Least count of the micrometer is 0.01 mm or 0.001cm.
Note** The least count is varies with the size of micrometer.
Bore gauge accurately measure the diameter of any hole known as bore gauge, It can be a scale, dial or digital type instrument. The most common bore gauge is dial type bore gauge, which comes with a dial gauge which is attached to the shaft and replacement rods, also known as measuring sleds, of different size to measure different hole dimensions. A bore gauge is a collective term for the tools that are unique to the process of accurately measuring holes.
It is usually calibrated in 0.001 inch (0.0025 cm) or 0.0001 inch (0.00025 cm).
These are a range of gauges that are use to measure a bore’s size, by transferring the internal dimension to a remote measuring tool. They are a direct equivalent of inside callipers and require the operator to develop the correct feel to obtain repeatable results.
Dial Bore Gauge
A dial bore gauge is a comparative instrument similar to a telescoping gauge, but includes a digital or analogy readout. The dial bore gauge must be set to the nominal value of the bore. it is measure the variation and direction of the bore from nominal. There are multiple ways to set this gauges to the nominal value. The most common method is using an outside micrometer that set to the nominal value. This is the quickest and least expensive way to set the dial bore gauge. This method is not most accurate because there can be high human error and variation in the micrometer is passed down into the dial bore gauge. The more accurate setting options include ring gauges (also called master rings) and designated bore gauge setting equipment that utilise gauge blocks or other standards.
When using a micrometer to set a dial bore gauge, the accuracy of the measurement will be 0.002 inches or 0.0508 millimetres.
A ring gauge can be use to obtain higher accuracy at a higher cost and higher time requirement. When a dial bore gauge is set using a ring gauge, overall accuracy can be within 0.0001 inches or 0.00254 millimetre.
For Example:-It is mainly use to measure cylinder bore, or turbocharger inside diameter.
A depth gauge is use to measure the depth of a slot, hole or any other surface of an object. It can be of scale, dial or digital type. The depth gauge can be a micrometer style type, a dial indicator type, or modified Vernier type tool, which means the measuring base is fitted on the reading scale of a micrometer, dial indicator or the Vernier scale.
For Example:- Depth gauge are use to measure the thread depth of tyre.
Feeler gauges a bunch of fine thickened steel strips of different thickness bundled together. The thickness of each strip marked on the surface of the strip. A feeler gauge is a tool use to measure gap widths. Feeler gauges are mostly use in engineering to measure the clearance between two parts
For Example:- It is mainly use to measure piston ring clearance, engine bearing clearance, tappet clearance, camshaft gape etc.